.content{
	width: 640px;
	height: 640px;
	margin: 0 auto;
	position: relative;
	/*border: 1px solid black;*/
}
.btn{
	width: 100%;
	height: 100%;
	position: absolute;
	left: 0;
	top: 0;
	background-color: rgba(0,0,0,0.3);
	z-index: 2;
}
.btn button{
	background: none;
	border: none;
	background-size: 100% 100%;
	cursor: pointer;
	outline: none;
	position: absolute;
	left: 50%;
	top: 50%;
}
.startBtn button{
	width: 200px;
	height: 150px;
	background-image: url(../images/startGame.png);/*中间隔两个文件夹，用俩点*/
	margin-left: -100px;
	margin-top:-75px;
}
.pauseBtn{
	display: none;/*暂停按钮一开始不显示，需要的时候再用JS显示出来*/
}
.pauseBtn button{
	width: 70px;
	height: 70px;
	background-image: url(../images/start.png);
	margin-left: -35px;
	margin-top:-35px;
}
#snakeWrap{
	width: 600px;
	height: 600px;
	background: #225675;
	border: 20px solid #7dd9ff;
	position: relative;
}
/*#snakeWrap div{
	width: 20px;
	height: 20px;
}*/
.snakeHead{
	background-image:url(../images/head.png);
	background-size:cover;/*和100%是一样的*/
}
.snakeBody{
	background-color: #9ddbb1;
	border-radius: 50%;
}
.food{
	background-image:url(../images/apple.png);
	background-size:cover;
}